Zeocin is a member of bleomycin family and acts by intercalating DNA causing DNA to cleavage and resulting in cell death. Sh ble gene codes a 13665 Dalton protein in order for the cell to be Zeocin® resistant. This protein can be synthesized on the antibiotic which prevents itself from binding to DNA and therefore, has resistance to Zeocin®. Zeocin® is effective for most aerobic cells and can also be used for screening mammalian cell lines, yeast and bacteria. Each type of cell screening requires different amount of Zeocin